Cellular fatty acid methyl ester profiles as a tool in the differentiation of members of the genus Mycobacterium

Abstract

The cellular fatty acid profiles of 84 strains belonging to 53 different species of the genus Mycobacterium were determined by gas liquid chromatography-mass spectrometry (GCMS). Two main types and four subtypes of fatty acid profiles were recognizable. The first main type is the G type, nominally referring to M. gordonae, members of which lack tuberculostearic acid or other 10-methyl branched-chain fatty acids, but contain normal saturated and unsaturated fatty acids. This type is further subdivided into the G alpha subtype that is characterized by 2-methyl tetradecanoic acid (2-Me-C14:0) as the only 2-methyl branched fatty acid. Strains belonging to the second main type, the T type, nominally referring to tuberculosis, contain tuberculostearic acid and other 10-methyl branched acids in addition to the normal saturated and unsaturated ones. This type has been further subdivided into three subtypes: the T alpha subtype that does not contain any 2-methyl branched fatty acids; the T beta subtype that contains both 2-methyl tetradecanoic (2-Me-C14:0) and 2,4-dimethyl tetradecanoic (2,4-DMe-C14:0) acids as 2-methyl branched fatty acids; the T gamma subtype which contains 2-methyl dodecanoic (2-Me-C12:0), 2,4-dimethyl dodecanoic (2,4-DMe-C12:0) and 2,4-dimethyl tetradecanoic (2,4-DMe-C14:0) acids as 2-methyl branched-chain acids. Fatty acid analysis showed a great homogeneity within the genus and the profiles produced were not very helpful in distinguishing between members of the genus Mycobacterium except for the identification of M. gordonae, M. kansasii, and M. gastri.